Zend PHP 5 Certification Study Guide, edited and produced by the publishers of php|architect, provides the most comprehensive and thorough preparation tool for developers who wish to take the Certification exam. 
The study guide comes in paperback edition as well as PDF format for immediate download.

In this book, PHP 5's co-creator and two leading PHP developers show you how to make the most of PHP 5's industrial- strength enhancements in any project—no matter how large or complex.
By Andi Gutmans, Stig Bakken, Derick Rethans.

The book introduces readers to PHP and MySQL for the purpose of creating dynamic Internet sites.
By Luke Welling, Laura Thomson.

Schlossanagle's book demonstrats that PHP is ready for enterprise Web applications by showing the reader how to develop PHP-based applications for maximum performance, stability, and extensibility. By George Schlossnagle.